Byproducts of Metabolism Flashcards
How are reactive oxygen species produced?
Some electrons are leaked from the ETC and prematurely reduce oxygen to form superoxide radicals
Why are ROS dangerous?
They cause damage to cells - including DNA, protein and membrane damage.
What is the function of superoxide dismutase (SOD)?
Catalyses the reaction of superoxide radicals together to form oxygen and hydrogen peroxide
What is the function of catalase?
Rapidly breaks down H2O2 into O2 and H2O (H2O2 is a ROS)
How can hydroxyl radicals be created?
Addition of iron ions to hydrogen peroxide (fenton reaction). Cannot be eliminated by enzymatic reactions
What is an oxidative burst?
Some cells of the immune system (such as neutrophils and monocytes) can rapidly produce a released of ROS. Do this by using NADPH oxidase
How is nitric oxide produced?
From arginine by the inducible enzyme nitric oxide synthase
What defences does the body have against ROS?
SOD, catalase, NADPH & glutathione, antioxidant vitamins, flavenoids and minerals
How do NADPH and GSH defend against ROS?
Catalysed by glutathione peroxidase and glutathione reductase
Describe the structure of glutathione
A tripeptide. Thiol group in cysteine can donate its H and therefore act as a reducing agent
List a few conditions with which oxidative stress is associated
Cancer (DNA), Alzheimers (protein damage and misfolding), Pancreatitis, CVD (lipid ox.), type 1 diabetes mellitus, emphysema (lung tissue)
How are lipid peroxides formed?
Reaction of unsaturated lipids with ROS - thought to lead to early CVD
